Abstract Detail

Physiology

Wang, Yue [1], Bailey, C. Donovan [2].

The regulatory mechanism of dormancy transition from endo-dormancy to non-dormancy in Polygonatum kingianum Coll.etHemsl rhizome bud.

Polygonatum kingianum Coll.etHemsl (P. kingianum) is an important traditional Chinese medicine, but the mechanism of its rhizome bud dormancy has not yet been studied systematically. In this study, three dormancy phases were induced under controlled conditions, and changes occurring during the transition were examined, focusing on phytohormones and the cell wall. As revealed by HPLC-MS (High Performance Liquid Chromatography-Mass Spectrometry) analysis, the endo- to non-dormancy transition was association with a reduced abscisic acid (ABA)/gibberellin (GA3) ratio, a decreased level of auxin (IAA) and an increased level of trans-zeatin (tZR). Transmission electron microscopy showed that plasmodesmata (PDs) and the cell wall of the bud underwent significant changes between endo- and eco-dormancy. A total of 95,462 differentially expressed genes (DEGs) were identified based on transcriptomics, and clustering and principal component analysis confirmed the different physiological statuses of the three types of bud samples. Changes in the abundance of transcripts associated with endogenous hormones, PDs and cell wall-loosening factors were analysed during the bud dormancy transition in P. kingianum. Furthermore, nitrilase 4 (NIT4) and tryptophan synthase alpha chain (TSA1), which are related to IAA synthesis, were identified as hub genes of the co-expression network, and strong interactions between hormones and cell wall-related factors were observed. Besides, it was also proved that 6-BA might promote the relief of rhizome bud endo-dormancy in P.kingianum by inhibiting ABA synthesis and improving IAA transport. This research will provide a good model for breaking rhizome bud dormancy in P. kingianum.